To avoid interference with a joint boot and other components, a so-called “pulled-together” tightening band is fixed by using a tool to pull together pulling claws formed on inner and outer band sections of a band member that has been formed in a ring shape.
For example, for the tightening band disclosed by Japanese Patent Number 2,652,136, both ends of a band member are overlapped and a fixing claw that protrudes inward on the outer band section is passed over and engages a bevel lead claw that protrudes outward on the inner band section, so that there is one engagement position. In this case, there is the risk of the tightened state becoming loose due to spring back and the like. For this reason, a first fixing claw and a second fixing claw are provided on the outer band section, a first bevel lead claw and a second bevel lead claw are provided on the inner band section, and when the pulling claws are pulled together to reduce the diameter, first the first fixing claw and the first bevel lead claw engage one another and the second fixing claw and the second bevel lead claw engage one another to fix the band sections, thereby improving the tightening force and the stability of the tightened state.
Also, when band ends of a band member that has been fitted onto the outer circumference of a boot and is temporarily held in a ring shape are pulled together using a tool such as pliers to reduce the diameter, the reactive force obtained from the tightened object when the band is tightened from the temporarily held state causes the band to return in the diameter-increasing direction, resulting in the engaging claw and the engaging hole engaging and fixing the band.
Rubber products used to be principally used as the material for boots, but in recent years resin boots formed by blow molding or the like have come into use. Compared to rubber boots, resin boots are thin with a material thickness of around 1 to 2 mm so that there is little deformation during tightening. Resin boots also exhibit high stiffness, which further inhibits deformation and as a result, it is difficult to obtain a reactive force on the band. Also to maintain a favorable seal, it is necessary to tighten resin boots with a large tightening force compared to rubber boots.
For this reason, since the reactive force from the boots is small, a tightening band that uses a construction where an elastic force builds up in the band member itself has been proposed. As examples of constructions where an elastic force builds up in the band member itself, a convex/concave section that can deform and/or holes may be formed in the band member, such as by forming a section that is V-shaped in cross section or W-shaped in cross section (see Japanese Laid-Open Patent Publication No. H7-198077) or by forming a through hole in the lengthwise direction and forming wavy sections on both sides of the through-hole (see Japanese Laid-Open Patent Publication No. H3-209035).
When the pulling claws of the tightening band disclosed by Japanese Patent Number 2,652,136 described above are engaged by a tool and clamped from the state where the band member is temporarily held in a ring shape, the first and second fixing claws that protrude inward on the outer band section pass over and engage the first and second bevel lead holes that protrude outward on the inner band section. For this reason, at the instant when the clamping force acts most strongly on the band member, the fixing claw and the bevel lead hole pass over one another and engage, so that there is the risk of top sections of the claws that protrude inward and/or outward being crushed or deformed. As a result, the engaging state of the claws becomes shallow and there is the risk of the tightening stability falling due to spring back. Also, since the overlapping band surfaces are rubbed by the claws as the diameter is reduced, when tightening and loosening operations are repeated, the top sections of the claws suffer abrasion so that clamping with a tool becomes difficult. When the tightening state is removed, both ends are released and spring outward, resulting in problems regarding handling and safety.
Since the second fixing claw and the second bevel lead claw are engaged by the diameter reducing operation after the first fixing claw and the first bevel lead claw have engaged, the stroke for pulling together the pulling claws is increased. This means that for a small-diameter tightening band, there is the risk of the band member collapsing due to the clamping.
In addition, when concave/convex sections and holes for providing an elastic force are formed in the band member itself as disclosed in Japanese Laid-Open Patent Publication No. H7-198077 and Japanese Laid-Open Patent Publication No. H3-209035, this leads to a reduction in the strength and the reliability of the band member. That is, since a large tightening force is required when the tightening band tightens an object such as a resin boot that hardly deforms, there is an increase in non-continuous sections (concave/convex sections and holes) in the circumferential direction in the band member, resulting in the risk of deterioration of the seal due to insufficient surface pressure.
Also, when the diameter of the band member that is temporarily held in the ring shape is reduced, tightening is carried out with fluctuations in tolerance for the tightened object being absorbed by a diameter reducing effect or diameter increasing effect of the band member, but since a resin boot that is a tightened object has high stiffness and hardly deforms, when the diameter is reduced there is the risk of the elastic limit of the band member being exceeded and plastic deformation occurring. Accordingly, there is the risk of the band member becoming stretched, resulting in it not being possible to achieve a strong tightening force.
The number of processes also increases and the manufacturing cost rises, and if the concave/convex section that provides an elastic force to a band member is increased, it becomes difficult to form the band member in a ring shape without deforming the concave/convex section. Fluctuations can therefore easily occur between products in dimensions such as the band diameter, resulting in the further problem of difficult handling.